Early Evolution Research Articles

The Source and Significance of Silicon in the Late Permian Dalong Formation, Northeastern Sichuan Basin

The Late Permian was a critical interval in geological history, during which dramatic changes occurred in the Earth’s surface system, and a set of black rock series rich in organic matter and silicon, the Dalong Formation, was deposited in the northeastern Sichuan Basin. We conducted a detailed sedimentological and petrological investigation integrated with (major and trace) element contents in the deep-water sequence of the Xibeixiang and Jianfeng sections. It demonstrates the source of silicon, tectonic background, and sedimentary environment of the Dalong Formation, and explores the influence of hydrothermal activities on organic matter enrichment. The results show that the upper part of the Dalong Formation contained more radiolarians in the Xibeixiang section compared to the Jianfeng section. Hydrothermal proxies such as Eu/Eu*, Al-Fe-Mn diagram, Al/(Al + Fe + Mn), and LuN/LaN suggest a biotic origin for the chert in the Dalong Formation in the Xibeixiang and Jianfeng sections, while the Xibeixiang section was slightly affected by hydrothermal activities. The La-Th-Sc diagram and the La/Sc and Ti/Zr crossplots point to a continental island arc and active continental margin origins for the Xibeixiang and Jianfeng sections. Combined with previous research, the silicon of the Dalong Formation in the northeastern Sichuan Basin is mainly derived from biological sources. The Xibeixiang section was affected by a small amount of hydrothermal fluid due to its proximity to the Paleo-Tethys Ocean and continental island arcs. Furthermore, the enrichment of organic matter was predominantly driven by high productivity, with minimal impact from hydrothermal activities. These insights hold significant research value and practical implications for shale gas exploration in the Sichuan Basin.

Neoproterozoic–early Paleozoic evolution of the southern Central Asian Orogenic Belt: Constraints from eclogites in the Beishan Orogenic Belt (NW China)

Eclogites provide important constraints on the processes of plate subduction, collision, and the overall tectonic evolution of orogens. The Gubaoquan eclogite is the only one identified in the Beishan Orogenic Belt, which constitutes the southernmost part of the Central Asian Orogenic Belt. U-Pb dating of the eclogite indicates a Neoproterozoic metamorphic age of 887 ± 7 Ma and an Ordovician age of 461 ± 15 Ma for the eclogite-facies metamorphism. Multi-proxy (zircon, monazite, rutile, and apatite) U/Th-Pb geochronology and trace element geochemistry reveal that they have experienced multiple tectonothermal events in the Neoproterozoic and Paleozoic. The protolith of the Gubaoquan eclogite is of continental origin, and along with the extensive distribution of the Neoproterozoic arc-related rocks probably formed near the periphery of Rodinia. Given the continental setting of the protolith of the Gubaoquan eclogite, we suggest that eclogite-facies metamorphism at ca. 461 Ma was due to subduction under the Shuangyingshan-Huaniushan arc, which is manifested as an arc-continental collision process.

Interactions between megathrust behavior and forearc deformation in the Andreanof segment of the Aleutian Subduction Zone, offshore Alaska, USA

To explore controls on megathrust behavior and its connection with forearc deformation, we studied the Andreanof segment of the Aleutian Subduction Zone (offshore Alaska, USA), which has a simple geological history as a relatively young intra-oceanic subduction zone. Here, the forearc shows greater uplift and compression in the strongly coupled Adak region compared to the weakly coupled Atka region. Using multichannel seismic reflection data, we found that the incoming plate in both regions exhibits similar characteristics along the segment, suggesting that its properties do not account for the varying megathrust behavior and forearc deformation. Instead, differences between the Atka and Adak regions in the thickness of the methane hydrate stability zone, as marked by a bottom-simulating reflector, suggest more heat advection, and thus dewatering, in the Adak region, where the more developed fault network may enable fluid drainage, thereby lowering pore pressure at the megathrust and promoting coupling. Higher coupling allows for seismic and stress cycling that would sustain forearc permeability by faulting. Our results suggest a feedback between deformation and coupling that may be active or latent in other more complex subduction zones but in concert with or masked by other factors.

The Peopling of Tajikistan by Homo sapiens denisovan

The study published in the previous issue of this journal addressed the dispersal and early morphological and genetic evolution of H. s. denisovan in Iran, following the split of the ancestral taxon H. heidelbergensis into two taxa, Neanderthals and Denisovans, in the Levant ~400 ka BP. The latter taxon was first described owing to the sequencing of DNA extracted from the fragment of the fifth finger phalanx from layer 11.2 of Denisova Cave, Altai. Having left the Levant 400–350 ka BP, Denisovans began to spread via Iran to Central Asia and eventually to the Altai. Humans appeared in Denisova Cave ~300 ka BP, having crossed vast territories of Central Asia different in terms of environment, climate, landscape, flora and fauna, and partly populated by aborigines—the late populations of H. erectus. Adapting to changing environments, assimilating native humans, and undergoing natural selection, H. s. denisovan evolved both genetically and morphologically. Here, the spread of Denisovans in Tajikistan will be discussed.

Preservation and early evolution of scalidophoran ventral nerve cord.

Ecdysozoan worms (Nematoida + Scalidophora) are typified by disparate grades of neural organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct the early character evolution of the nervous system via the exceptional preservation of extinct representatives. We focus on their nervous system as it appears in early and mid-Cambrian fossils. We show that some of the oldest known representatives of the group either preserved in carbonaceous compression (early and mid-Cambrian Burgess-type preservation) or secondarily phosphatized in three dimensions (e.g., basal Cambrian Kuanchuanpu Formation, ca. 535 million years) had an unpaired ventral nerve cord (VNC) that ran along the trunk in an eccentric position as in modern priapulids and nematodes. A phylogenetic analysis integrating these fossil data suggests that ancestral scalidophorans had an unpaired VNC and that paired nervous systems probably evolved independently in Kinorhyncha and Loricifera, and, more importantly, in panarthropods in possible relation with the rise of paired appendages and bilaterally coordinated motricity.

Plio-Pleistocene Environmental Changes Drove the Settlement of Aotearoa New Zealand by Australian Open-Habitat Bird Lineages.

In a changing environment, vacant niches can be filled either by adaptation of local taxa or range-expanding invading species. The relative tempo of these patterns is of key interest in the modern age of climate change. Aotearoa New Zealand has been a hotspot of biogeographic research for decades due to its long-term isolation and dramatic geological history. An island with high levels of faunal endemicity, it is a system well suited to studying the relative effects of insitu evolution versus dispersal in determining faunal assemblages, while its turbulent climate and geological history provide valuable insights into the evolutionary impacts of environmental changes. Such investigations are of urgent importance given predicted climate change and human impacts rapidly affecting environments globally. Here, we analyse the divergence dates of nearly all endemic Aotearoa New Zealand bird species from their overseas relatives to assess the role of environmental changes in driving speciation and colonisation, with special regard to cooling climate during the Pliocene and Pleistocene. We uncover a wave of colonisation events by Australian open-habitat adapted species since the Pliocene that peaked at the beginning of the Pleistocene. Furthermore, we highlight an even distribution of divergence dates in forest-adapted taxa through time, consistent with millions of years of extensive forest cover. Finally, we note parallels to the modern-day establishment of new bird populations from Australia and suggest this is largely influenced by anthropogenic land-use patterns. This research contributes to the growing body of work recognising the long-lasting impacts of Pleistocene climate change on Aotearoa New Zealand's avifauna, and reinforces biological invasions as a key evolutionary response to changing environmental conditions.

New Silurian aculiferan fossils reveal complex early history of Mollusca.

Mollusca is the second most species-rich animal phylum, but the pathways of early molluscan evolution have long been controversial1-5. Modern faunas retain only a fraction of the past forms in this hyperdiverse and long-lived group. Recent analyses6-8 have consistently recovered a fundamental split into two sister clades, Conchifera (including gastropods, bivalves and cephalopods) and Aculifera9, comprising Polyplacophora ('chitons') and Aplacophora. Molluscan evolution in toto is characterized by plasticity in body-plan characters10, but historically aculiferans have been interpreted as more conservative10,11. The few completely preserved aculiferan or aculiferan-like fossils from the early Palaeozoic12-19 have been largely regarded as transitional forms that inform questions of character polarity between the extant polyplacophoran and aplacophoran body forms20,21. The history of early aculiferans, and the morphological and ecological range that they occupied, remain inadequately sampled. Here we describe two new three-dimensionally preserved aculiferan species from the Silurian Herefordshire Lagerstätte22,23, which substantially extend the morphological and ecological range of the clade. Phylogenetic analyses indicate positions within a complex nexus of taxa and suggest reversals in the states of fundamental characters such as the presence of valves and the nature of the foot. In contrast to previous hypotheses of morphological conservatism, evolution in early aculiferans generated a profusion of unusual forms comparable to the diversification of other crown-group molluscs.

Morphology and phylogeny of Itaspiella helgolandica, an interstitial marine flatworm with circumpolar distribution

Flatworms in the family Otoplanidae Hallez, 1892, are ubiquitous inhabitants of the swash zone of marine sandy beaches worldwide. We present new insights into the morphology and phylogenetic position of the otoplanid Itaspiella helgolandica (Meixner, 1938) based on specimens sampled in northern Norway. While the species was originally described from the German coast, it has since been reported in the High Arctic as well as in Greenland, Canada and Alaska, indicating that it has a circumpolar distribution. Apart from these reports, I. helgolandica has received marginal scientific attention beyond the original species description, and apart from drawings, there is not much detailed data available of its morphology. We employ antibody staining and confocal laser microscopy to provide detailed morphological information on the ciliation, myoanatomy and genital organs of specimens of I. helgolandica and compare their morphology with other accounts of the species from across the Arctic. We investigate the phylogenetic relationships of Itaspiella Ax, 1955 through a Bayesian/RAxML analysis of 28S sequences and confirm the morphologically underpinned notion that this genus sits within the subfamily Otoplaninae Hallez, 1910, as the sister taxon to Xenotoplana Ax, Weidemann & Ehlers, 1978. In light of our findings, we explore the question of the apparent circumpolar distribution of Itaspiella in the context of the larger “meiofauna paradox” and touch upon various evolutionary phenomena that may have contributed to phenotypic stability despite its limited dispersal capabilities and the vicariance imposed by the complex recent geological history of the Arctic.

New material of the Early Devonian sarcopterygian Styloichthys changae illuminates the origin of cosmine

The Early Devonian sarcopterygian Styloichthys changae provides substantial information to resolve the phylogenetic relationships of early sarcopterygians. Its dermal bones show a cosmine surface with relatively large pores and a unique histological condition, which is essential to understanding the early evolution of the dermoskeleton in sarcopterygians. However, more detailed histological information on this taxon is needed. Here, we present new data about the morphology and histology of dermal bones and scales of S. changae based on two semi-articulated specimens. The scales bear parallel ridges and relatively large pores on their external surface resembling those of the dermal bones, showing an intermediate condition between stem sarcopterygians and crown sarcopterygians. We recognize three stages in the growth series of S. changae scales. The growth pattern of the cosmine layer undergoes two significant changes: from a superpositional pattern to a continuous areal pattern and then to a discontinuous areal pattern. In addition, the new data indicate that the pore-canal system predates the enamel-dentine complex of cosmine. This work supports the hypothesis that the cosmine arose step by step in sarcopterygians and provides more details on the evolutionary development pattern of cosmine.

Unravelling viral ecology and evolution over 20 years in a freshwater lake.

As freshwater lakes undergo rapid anthropogenic change, long-term studies reveal key microbial dynamics, evolutionary shifts and biogeochemical interactions, yet the vital role of viruses remains overlooked. Here, leveraging a 20 year time series from Lake Mendota, WI, USA, we characterized 1.3 million viral genomes across time, seasonality and environmental factors. Double-stranded DNA phages from the class Caudoviricetes dominated the community. We identified 574 auxiliary metabolic gene families representing over 140,000 auxiliary metabolic genes, including important genes such as psbA (photosynthesis), pmoC (methane oxidation) and katG (hydrogen peroxide decomposition), which were consistently present and active across decades and seasons. Positive associations and niche differentiation between virus-host pairs, including keystone Cyanobacteria, methanotrophs and Nanopelagicales, emerged during seasonal changes. Inorganic carbon and ammonium influenced viral abundances, underscoring viral roles in both 'top-down' and 'bottom-up' interactions. Evolutionary processes favoured fitness genes, reduced genomic heterogeneity and dominant sub-populations. This study transforms understanding of viral ecology and evolution in Earth's microbiomes.

Chemical Evolution of the Solid Earth and Volcanology (NSF)

Chemical Evolution of the Solid Earth and Volcanology (NSF)

Flexibility in PAM Recognition Expands DNA Targeting in xCas9.

xCas9 is an evolved variant of the CRISPR-Cas9 genome editing system, engineered to improve specificity and reduce undesired off-target effects. How xCas9 expands the DNA targeting capability of Cas9 by recognizing a series of alternative Protospacer Adjacent Motif (PAM) sequences while ignoring others is unknown. Here, we elucidate the molecular mechanism underlying xCas9's expanded PAM recognition and provide critical insights for expanding DNA targeting. We demonstrate that while wild-type Cas9 enforces stringent guanine selection through the rigidity of its interacting arginine dyad, xCas9 introduces flexibility in R1335, enabling selective recognition of specific PAM sequences. This increased flexibility confers a pronounced entropic preference, which also improves recognition of the canonical TGG PAM. Furthermore, xCas9 enhances DNA binding to alternative PAM sequences during the early evolution cycles, while favouring binding to the canonical PAM in the final evolution cycle. This dual functionality highlights how xCas9 broadens PAM recognition and underscores the importance of fine-tuning the flexibility of the PAM-interacting cleft as a key strategy for expanding the DNA targeting potential of CRISPR-Cas systems. These findings deepen our understanding of DNA recognition in xCas9 and may apply to other CRISPR-Cas systems with similar PAM recognition requirements.

Most High-density Exoplanets Are Unlikely to Be Remnant Giant Planet's Cores

Some exoplanets have much higher densities than expected from stellar abundances of planet-forming elements. There are two theories—metal-rich formation hypothesis and naked core hypothesis—that explain how formation and evolution can alter the compositions and structures of rocky planets to diverge from their primordial building blocks. Here we revisit the naked core hypothesis, which states that high-density planets are remnant cores of giant planets that remain in a fossil-compressed state, even after envelope loss. Using a planetary interior model and assuming energy-limited atmospheric escape, we show that a large fraction, if not all, of the iron–silicate core of a giant planet is molten during the planet's early evolution. Upon envelope loss, the molten part of the planets can rapidly rebound owing to low viscosity, resulting in a decrease in radius by at most 0.06%, if they had hydrogen/helium envelopes, or by at most 7%, if they had H2O envelopes, compared to self-compressed counterparts with the same core mass fraction. Based on our findings, we reject the hypothesis that all high-density exoplanets are naked cores with Kolmogorov–Smirnov p-value ≪0.05 for both envelope compositions. We find that some high-density exoplanets can still possibly be naked cores, but the probabilities are lower than ∼1/2 and ∼1/3 for the ice giant and gas giant scenario, respectively, in 95% of the cases. We conclude that most high-density exoplanets are unlikely to be remnant giant planet cores.

Cranial osteology and neuroanatomy of the late Permian reptile Milleropsis pricei and implications for early reptile evolution.

Millerettidae are a group of superficially lizard-like Permian stem reptiles originally hypothesized as relevant to the ancestry of the reptile crown group, and particularly to lepidosaurs and archosaurs. Since the advent of cladistics, millerettids have typically been considered to be more distant relatives of crown reptiles as the earliest-diverging parareptiles and therefore outside of 'Eureptilia'. Despite this cladistic consensus, some conspicuous features of millerettid anatomy invite reconsideration of their relationships. We provide a detailed description of the late Permian millerettid Milleropsis pricei using synchrotron X-ray phase-contrast micro-computed tomography focusing on the cranial anatomy of three individuals known from a burrow aggregation. Our data reveal a suite of neuroanatomical features Milleropsis shares with neodiapsids that are absent both in other 'parareptiles' and in early diverging groups of 'eureptiles'. Traits shared between Milleropsis and neodiapsids include: the presence of a tympanic emargination on the quadrate, quadratojugal and squamosal, the loss of epipterygoid contribution to the basicranial articulation suggesting a more kinetic palatoquadrate, the absence of a sphenethmoid and the pathway of the abducens nerve through the braincase. Our findings suggest that the early reptile neurocranium, a region poorly sampled in phylogenetic analyses due to relative visual inaccessibility and poor preservation, has the potential to inform the phylogenetic relationships of early reptiles.

Enantioselective interactions of aminonitrile dimers.

Enantioenrichment of amino acids is essential during the early chemical evolution leading to the origin of life. However, the detailed molecular mechanisms remain unsolved. Dimerization of enantiomers is the first molecular process in the nucleation of deposition and crystallization, which are both essential for enantioenrichment. Here, we report the enantioselective interactions of dimers of chiral intermediates, i.e., aminonitriles, in both gas and water environments based on density functional theory (DFT) and more accurate coupled-cluster (CC) calculations. We show that all the aminonitriles stabilize the homochiral dimer preferentially to the heterochiral dimer in the gas phase, while this trend was not observed in water. The energies of the enantioselective interactions in aminonitriles are substantially lower compared to those in amino acids, especially isovaline. These results suggest that prebiotic enhancements of enantiomeric excess are more likely to occur in amino acids than in the aminonitrile intermediates.

EWOCS-III: JWST observations of the supermassive star cluster Westerlund 1

Context. The typically large distances, extinction, and crowding of Galactic supermassive star clusters (stellar clusters more massive than 104 M⊙) have so far hampered the identification of their very low mass members, required to extend our understanding of star and planet formation, and early stellar evolution, to the extremely energetic star-forming environment typical of starbursts. This situation has now evolved thanks to the James Webb Space Telescope (JWST), and its unmatched resolution and sensitivity in the infrared. Aims. In this paper, the third of the series of the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS), we present JWST/NIRCam and JWST/MIRI observations of the supermassive star cluster Westerlund 1. These observations are specifically designed to unveil the cluster members down to the brown dwarf mass regime, and to allow us to select and study the protoplane-tary disks in the cluster and to study the mutual feedback between the cluster members and the surrounding environment. Methods. Westerlund 1 was observed as part of JWST GO-1905 for 23.6 hours. The data have been reduced using the JWST calibration pipeline, together with specific tools necessary to remove artifacts, such as the 1 /f random noise in NIRCam images. Source identification and photometry were performed with DOLPHOT. Results. The MIRI images show a plethora of different features. Diffuse nebular emission is observed around the cluster, which is typically composed of myriads of droplet-like features pointing toward the cluster center or the group of massive stars surrounding the Wolf–Rayet star W72/A. A long pillar is also observed in the northwest. The MIRI images also show resolved shells and outflows surrounding the M-type supergiants W20, W26, W75, and W237, the sgB[e] star W9 and the yellow hypergiant W4. Some of these shells have been observed before at other wavelengths, but never with the level of detail provided by JWST. The color-magnitude diagrams built using the NIRCam photometry show a clear cluster sequence, which is marked in its upper part by the 1828 NIRCam stars with X-ray counterparts. NIRCam observations using the F115W filter have reached the 23.8 mag limit with 50% completeness (roughly corresponding to a 0.06 M0 brown dwarf).

Environmental changes and uplift of the Qinghai-Tibet Plateau drive genetic diversification and speciation of the birds.

Being the most magnificent plateau in elevation and size on Earth, the Qinghai-Tibet Plateau has a profound impact on biodiversity due to the unique geographic and climatic conditions. Here we review the speciation patterns and genetic diversity of the birds from the Qinghai-Tibet Plateau in relation to the geological history and climatic changes. First, the uplift of the Qinghai-Tibet Plateau forms a geographic barrier and promotes interspecific and intraspecific genetic differentiation. Second, the uplift of the Qinghai-Tibet Plateau has provided new ecological niches for many endemic birds and facilitated their speciation. Third, the emigration and immigration of bird species between the Qinghai-Tibet Plateau and adjacent zoological regions have promoted species divergence, colonization and dispersal. Furthermore, Pleistocene glaciations and associated climate change drive postglacial colonization and lead to secondary contact, which influenced the genetic divergence of the conspecific populations and sister species. The multi-omics approach has increasingly been used in the studies on the ecological adaptive evolution of birds in Qinghai-Tibet Plateau. Future studies should focus on the role of geological and climatic factors in species differentiation, develop integrative approach with multi-omics methods, and explore the ecological mechanisms of high-elevation adaptation of plateau species. As an important region for biodiversity conservation, more efforts should be implemented to maintain the stability and sustainability of the Qinghai-Tibet Plateau and its ecosystem in light of global change.

Subsurface geology of the Torino metropolitan area (Westernmost Po Plain, NW Italy)

ABSTRACT The 1:100,000 subsurface geological map of the Torino metropolitan area covers ∼900 km2 in the westernmost Po Plain, an area of great relevance being crossed by the late Neogene to Quaternary ‘Torino Hill Front’ (THF), a tens of kilometers long, NW-verging buried and blind thrust. The map provides an updated representation of the bedrock geology below the late Early Pleistocene-Holocene Alpine-sourced fluvial blanket, relying on novel correlation of shallow water well and borehole logs. The map describes how the syn-depositional thrust-related folding pulses affected the early Piacenzian-early Middle Pleistocene tectono-stratigraphic evolution of this sector. Our results demonstrate that the deposition of the lower Piacenzian shallow marine succession and then of the Piacenzian to Calabrian alluvial record was controlled by the stepwise propagation of the THF, and suggest that this thrust was apparently sealed by the late Early Pleistocene unconformity. Gentle folding characterized the late Early Pleistocene-early Middle Pleistocene time interval.

On the use of remote sensing data to study the geological structure and forecast mineral resources of the Shu-Ile suture

Purpose. This article focuses on analyzing the geodynamic processes that underline the formation of the Shu-Ile ore zone. The study is based on the principles of plume tectonics, which have gained widespread recognition in the geological community in recent decades. Methods. The article considers the main aspects of the plume-tectonic concept, including the mechanisms of mantle material flows and their impact on regional geological processes. Special attention is paid to analyzing tectonic and magmatic events associated with forming the Shu-Ile ore zone within plume-tectonic mechanisms. Findings. The study highlights the critical role of mantle plumes in influencing the geodynamic evolution of the Shu-Ile ore zone. Geochemical and geophysical evidence reveals the composition and characteristics of magmatic rocks, demonstrated a direct link between mantle plume processes and ore potential in the region. The findings underscore how mantle-derived material flows have significantly contributed to the formation of geological structures and mineral resources. Originality. The study results offer a new perspective on the geological history of the Shu-Ile ore zone, emphasizing the significance of plume tectonics as a critical factor in the geodynamic processes involved in ore deposit formation. Practical implications. This research is practical for geological studies and forecasting promising ore deposits in this region. It may serve as a basis for further research on plume tectonics and its influence on forming geological structures and mineral resources.

Sedimentary facies and grain size distribution; Insights into Ogwashi-Asaba Formation, Niger Delta Basin

The Niger Delta is renowned for being one of the most productive hydrocarbon provinces globally. This productivity is primarily attributed to its complex geological history, which is marked by intricate stratigraphy and various sedimentary facies. These sedimentary facies, which are distinct bodies of sediment with specific characteristics, provide essential information about past environments and sedimentary processes, about the complex stratigraphy and diverse sedimentary facies. Stratigraphic sequences in the Niger Delta include alternating layers of sandstones, shales, and siltstones. Sediment samples were collected with cores too, from the Ogwashi-Asaba formation, and a detailed field analysis was documented. Grain size, petrographic, and geochemical analysis were carried out in the lab, from the samples collected. The analyzed parameters suggest that the sandstone samples from the Ogwashi-Asaba Formation are predominantly fluviatile. Graphic Mean (Mz) ranges from 1.4 to 2.1 phi. Grain Size Composition 2-20% very fine sand, 6-66% fine sand, 45-87% medium to coarse sand, and 70-100% very coarse sand. Sorting (σ1) ranges from 1.1 to 2.1 phi, with 64.71% of sediments being very poorly sorted and 35.29% poorly sorted. Graphic Skewness (Sk) ranges from -0.6 to +0.5, indicating varying energy conditions. Graphic Kurtosis (KG): Ranges from 0.8 to 1.9, with curves varying from leptokurtic to platykurtic. These sedimentary processes shaping the Ogwashi-Asaba formation creates a diverse stratigraphy and a variety of sedimentary facies. Each provides valuable insights into past environmental conditions and sedimentary dynamics. A comprehensive understanding of these processes enhances the potential for hydrocarbon exploration and the reservoir characterization of the province.